Device and method for dispensing fluid materials

ABSTRACT

The invention provides a device and method for dispensing fluid materials from a product reservoir onto a substrate. The device includes at least one dispensing nozzle having at least one inner conduit leading to an exit port and adaptable to be in fluid communication with a supply source for the fluid dispensable material. The nozzle further comprises an end portion defining the exit port such that a ribbon of fluid dispensable material can be applied to the substrate. The nozzle is mountable on means that effect substantially perpendicular free movement of the nozzle relative to the substrate, such that the end portion of the nozzle maintains contact with the fluid material applied to the substrate. During dispensing, movement towards the substrate is effected by an applied force and movement away from the substrate is effected by a thrust exerted by the dispensed fluid material against said end portion of the nozzle and the dispensable material in the exit port.

FIELD OF INVENTION

The invention relates to a dispensing device and method for dispensingfluid materials including liquids and pastes, especially for use withliquid gasketing materials, particularly for the automotive industry.

BACKGROUND OF THE INVENTION

Anaerobic adhesives are used widely in industry for many applications.One particular application is the use of such adhesives as sealants inthe provision of gaskets on flanges for use in the combination of partsin the automotive industry. Traditionally, there are two ways to apply aliquid gasketing material in the automotive industry, roboticapplication or screen printing. Robotic application includes theincorporation of a nozzle onto a programmed automated arm which thenmoves the nozzle about a substrate in a predetermined manner. Roboticapplicators have the advantage over screen printing that as the adhesiveis dispensed directly from a single nozzle to the substrate, there is nolarge surface of adhesive which results in the applicator being moreflexible and cleaner. In comparison, as screen printing involves placinga screen over the substrate it only requires the same amount of time forthe application of adhesive regardless of the complexity of thedispensed pattern geometry. As a result of advantages of roboticapplication, there has been a trend towards robotic dispensing but it isdesirable to improve the speed and quality of application in suchdispensing.

The conventional dispensing equipment uses a needle which is usuallypositioned 2-3 mm above the substrate to which the adhesive is to beapplied. Desirably the substrate is presented at the same height eachtime, such that the adhesive is applied to a substantially planarsubstrate. The substrate is desirably mated with stops to ensureconsistent substrate height. However, this is not always possible.

In the provision of liquid gasketing materials it is common to useanaerobic adhesives. These adhesives are so called because they do notcure in the presence of air. As such the adhesives are typicallysupplied in mechanically sealed permeable containers with air containedtherein The nature of the constituents of the adhesive, and the factthat it is the absence of air that facilitates curing means it isessential for the adhesive to contact air during storage and prior toapplication. Otherwise, the shelf life of the adhesive becomescompromised.

As such, it is not uncommon for these products have air bubblescontained therein. The presence of the air bubbles in the adhesive tendsto cause breaks in the flow from the container. After the passage of abubble out of the dispensing tip, normal adhesive is dispensed again,which re-establishes the continuity of the adhesive bead. The height ofthe nozzle from the substrate and the speed of the robotic dispensingarm affect the quality of adhesive bead being dispensed. If a breakoccurs and the nozzle is at a large distance away from the substratethen the length of the break as seen on the substrate will be large;similarly it will be understood that the greater the nozzle speed, thelarger the break on the substrate.

In commercial application of adhesives to form gaskets on flanges it isnot always possible to present the flange substrate to the dispensingnozzle in a consistent planar manner. In such situations the substratecan be presented at varying heights and angles to the robotic dispensingarm. Although it is possible to program the robot to accuratelymanoeuvre around obstacles on a well presented flange, it is difficultto compensate for fluctuations arising from a badly presented flange.The inability of the robotic dispensing arm to compensate for suchfluctuation may result in poorly-applied gasketing materials.

In common applications the smallest adhesive beads that should bedispensed are of approximately 2 g/m², which is recommended in industrypractice to be achieved using a nozzle having a port diameter of 0.8 mm.This preferred port diameter is calculated from a relationship thatexists between the cross sectional area of the nozzle port and velocityof fluid product exiting said port and the area of the dispensed bead onthe substrate and the velocity of the robot arm. To ensure that anadequate area of adhesive is dispensed using predetermined recommendedrelationships between the robot and product speed it is calculated thata port diameter of 0.8 mm is sufficient. Depending on the viscosity ofthe adhesive, the dispensed adhesive bead may be dispensed in agenerally semi-circular/circular section on the substrate. It ispreferable to achieve the adhesive velocity in the nozzle ofapproximately twice that of the robotic dispensing arm speed. Thisminimises the effect of air bubbles entrained in the adhesive. Dependingon the application one can tolerate a break of up to about 16 mm in thedispensed bead of adhesive as the adhesive will flow when the substratesare brought together. In the range of about 16-22 mm one observesnecking, which although it will heal itself, may form a gasket which isnot constant across the width of the substrate. At a gap greater thanabout 22 mm one may observe a complete break, which results in anincomplete seal when the substrates are brought together and the jointmay leak and will either have to be reassembled or repaired.

When the adhesive is applied as a gasketing material to a flange, it iscommon to use vision inspection systems to ensure quality of applicationof the adhesive bead, especially when considering the cost of visualinspection as opposed to the cost of reassembly or repair resulting frompoorly applied gasketing material. If the vision inspection systemsdetect any break in the applied bead it is common practice to manuallyapply additional adhesive at the point of breakage. Additional teststhat may be incorporated include the “blow-out” test, which involves theintegrity testing of two mated and thereby sealed flanges. Aftercomplete assembly the unit is pressurised to approximately ½ bar, theability of the unit to maintain the pressure being indicative of anadequate seal.

There have been proposals to alter the adhesive product so as tominimise the possibility of breaks occurring in the dispensed bead. Thismay be achieved by reducing the amount of air within the adhesiveproduct, however, as noted, this comes with a cost of a reduction ofshelf life. By refrigeration it is possible to counteract the shelf lifereduction somewhat but even so the shortened shelf-life is an addedexpense and results in problems for manufacturers. Accordingly, it wouldbe desirable to provide a dispensing system which allows for a bead of aliquid product to be applied to a surface with little to no interruptionin the bead from air entrained in the liquid product.

SUMMARY OF THE INVENTION

The present invention provides a dispensing device and a process forusing said device which allows for the application of high qualitybeading, in particular in the application of anaerobic adhesives orsealants to form gaskets. The invention is also applicable to otherfluid dispensable materials.

In one aspect the invention provides a device suitable for thedispensing of a fluid dispensable material in ribbon form to asubstrate. The device includes

at least one dispensing nozzle having at least one inner conduit leadingto an exit port and adaptable to be in fluid communication with a supplysource for the fluid dispensable material, the nozzle having an endportion defining the exit port such that a ribbon of fluid dispensablematerial can be applied to the substrate, and

means for mounting the nozzle for substantially perpendicular freemovement relative to the substrate such that the end portion of thenozzle maintains contact with the fluid material applied to thesubstrate, movement towards the substrate being effected by an appliedforce and movement away from the substrate being effected by a thrustexerted by the dispensed fluid material against said end portion of thenozzle and the dispensable material in the exit port.

The invention also provides an apparatus for dispensing a fluid productonto a substrate, the apparatus comprising a nozzle and means formounting the nozzle with at least one degree of freedom allowingmovement of the nozzle relative to the substrate with movement towardsthe substrate being effected by a substantially constant force andmovement away from the substrate being effected by a force related tothe pressure exerted by the dispensed fluid on the nozzle.

The invention also provides a method for dispensing a fluid dispensablematerial to a substrate comprising the steps of

mounting a dispensing nozzle in a manner which allows substantiallyperpendicular free movement of the nozzle relative to the substrate,

facilitating the application of an applied force on the dispensingnozzle to effect movement of the nozzle in a direction towards thesubstrate,

supplying the fluid dispensable material to an exit port which isdefined by an end portion of the nozzle, applying the material to thesubstrate, and controlling the applied force in relation to a thrustexerted by the dispensed fluid material on the end portion of the nozzleand the dispensable material therein such that the end portion of thenozzle maintains contact with the dispensed material applied to thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional diagram, not to scale, showing theapplication of a dispensed bead of adhesive according to the prior art,

FIG. 2 is a transverse section across a bead of adhesive as dispensedaccording to FIG. 1,

FIG. 3 is a functional block diagram of a robotic dispensing system foruse with a device according to the present invention,

FIG. 4 is a diagram showing a section through a dispensing nozzleillustrating the method of the invention, for applying adhesive to asubstrate,

FIG. 5 is a similar diagram showing the effect of the movement of thenozzle of FIG. 4 on the dispensed adhesive product,

FIG. 6 is a perspective view of a device according to the inventionshowing a dispensing nozzle and the means for mounting the nozzle to arobot arm,

FIG. 7 is a plan view of the device of FIG. 6,

FIG. 8 is a part sectional side elevation of part of the device of FIG.7, the section being on the line X—X, additionally showing a substrateand the positioning of the device before the dispensing procedure isinitiated

FIG. 9 is a side elevation showing the positioning of the device of FIG.8 relative to the substrate during dispensing of adhesive on to thesubstrate,

FIG. 10 is a magnified section of the nozzle portion of the device ofFIG. 8 during dispensing

FIG. 11 is a section through a nozzle in accordance with a secondembodiment of the invention,

FIG. 12 is a section through a nozzle in accordance with a thirdembodiment of the invention,

FIG. 13 is a perspective view from above of an alternative mountingmethod for the nozzle of the present invention,

FIG. 14 is a perspective view from below of the embodiment of FIG. 13,and

FIG. 15 is a transverse section through a dispensed bead of adhesive asdispensed according to the method of the present invention,

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a dispensing device and a process forusing said device which allows for the application of high qualitybeading, in particular in the application of anaerobic adhesives orsealants in a ribbon form to form gaskets on suitable substrates. Theinvention is also applicable to other fluid dispensable materials.

In one aspect the invention provides a device suitable for thedispensing of a fluid dispensable material in ribbon form to asubstrate. The device includes at least one dispensing nozzle having atleast one inner conduit leading to an exit port and adaptable to be influid communication with a supply source for the fluid dispensablematerial, the nozzle having an end portion defining the exit port suchthat a ribbon of fluid dispensable material can be applied to thesubstrate, and

means for mounting the nozzle for substantially perpendicular freemovement relative to the substrate, such that the end portion of thenozzle maintains contact with the fluid material applied to thesubstrate, movement towards the substrate being effected by an appliedforce and movement away from the substrate being effected by a thrustexerted by the dispensed fluid material against said end portion of thenozzle and the dispensable material in the exit port.

The thrust exerted by the dispensed fluid material against the endportion of the nozzle may be thought of as a buoyant force, and thethrust exerted includes the thrust exerted by the dispensed fluidmaterial on the fluid dispensable material present in the exit port aswell as on the end portion of the nozzle i.e. the thrust exerted on thewhole surface area within the perimeter of the end portion of thenozzle. The applied force effecting movement towards the substrate maysuitably be gravity modulated by control means such as a spring.

Although the invention is not limited by any theory it is thought thatthe buoyant force is related to a pressure integral or summation ofpressure exerted by the dispensed material across the nozzle endportion.

The thrust exerted by the dispensed fluid material is desirablysubstantially equal in magnitude to the applied force such that thenozzle floats on the dispensed ribbon of material, and an equilibriumbetween the movement towards the substrate and movement away from thesubstrate is desirably maintained during the dispensing procedure.

The dispensed fluid is desirably an adhesive/sealant and more desirablyan anaerobic adhesive/sealant, which may suitably have a DIN viscosityin the range 7,500 to 90,000 mP·s.

In one embodiment, the device includes a single nozzle having a singleinner conduit, the end portion of which is preferably an annular shapedsurface, which facilitates the omni-directional movement of the nozzleacross the substrate under robotic control.

The end portion of the nozzle may desirably be mounted so that an endface thereof is substantially parallel to said substrate. The end facesuitably is a flat face. While the dimensions of the end portion willvary depending upon the desired dimensions of the ribbon and theviscosity of the fluid material to be dispensed in exemplary embodimentsthe outside diameter of the end portion is in the range from about 2.5mm to about 10 mm, particularly about 4 to about 6 mm, and the diameterof the exit port defined by said end portion is in the range from about1 mm to about 5 mm, particularly about 2 to about 3 mm. Using such anozzle of outside diameter of 4 mm it is possible to apply a ribbon ofwidth 5 mm.

The invention also provides an apparatus for dispensing a fluid productonto a substrate, the apparatus comprising a nozzle and means formounting the nozzle with at least one degree of freedom allowingmovement of the nozzle relative to the substrate with movement towardsthe substrate being effected by a substantially constant force acting onthe nozzle in a direction towards the substrate, and movement away fromthe substrate being effected by a force related to the pressure exertedby the dispensed fluid on the nozzle.

The invention also provides a method for dispensing a fluid dispensablematerial to a substrate comprising the steps of

mounting a dispensing nozzle in a manner which allows substantiallyperpendicular reciprocal movement of the nozzle relative to thesubstrate,

facilitating the application of an applied force on the dispensingnozzle to effect movement of the nozzle in a direction towards thesubstrate,

supplying the fluid dispensable material to an exit port which isdefined by an end portion of the nozzle, applying the material to thesubstrate, and controlling the applied force in relation to a thrustexerted by the dispensed fluid on the end portion of the nozzle and thedispensable material therein such that the end portion of the nozzlemaintains contact with the dispensed material applied to the substrate.

The substantially constant force which effects movement towards thesubstrate may be substantially equal in magnitude to the force effectingmovement away from the substrate. The force which effects movement ofthe nozzle towards the substrate may act directly or indirectly on thenozzle.

The supply source for the fluid dispensable material is suitably aproduct reservoir of conventional type, particularly, a productreservoir such as is conventionally used for anaerobic adhesives. Theproduct reservoir is desirably pressurised such that the product isdispensed under pressure.

It is thought that the force related to the pressure exerted by thedispensed fluid on the nozzle is a buoyant force which is a function ofone or more of the following:

a) the pressure exerted by the applied fluid on the nozzle,

b) the pressure exerted by the applied fluid on the fluid in the exitport and,

c) the distance of the nozzle away from the substrate.

The product being dispensed may contain air bubbles which while beingdispensed result in less pressure being applied on the nozzle in thedirection away from the substrate. In order to maintain the buoyancyforce substantially constant, this reduction in pressure is compensatedby a reduction in distance of the nozzle from the substrate. The smallergap between the nozzle and substrate acts to increase the buoyancyforce. When the air bubble has been dispensed the pressure of thedispensed liquid effects more pressure on the nozzle, which results inthe gap between the nozzle and the substrate increasing to maintain thebuoyancy force constant.

The interaction between the nozzle and the dispensed product allows thenozzle to adjust its height relative to the substrate as a result ofvariations in the dispensed product, while the nozzle is maintained insubstantially intimate contact with the ribbon of dispensed fluid duringthe dispensing procedure.

In a preferred embodiment a ribbon of material is applied onto thesubstrate at a thickness (perpendicular to the substrate) greater thanthe surface roughness of the substrate, i.e. greater than the maximumheight of any surface projections above the general plane of thesubstrate surface.

In an alternative embodiment wherein the buoyancy force is less than theforce acting towards the substrate then the nozzle may ride on thesubstrate resulting in local points of contact between the substrate andthe nozzle.

In the method of the invention, the fluid may suitably be laid onto thesurface in a ribbon of material.

The invention will now be described with reference to the followingillustrated examples which are not intended to limit the invention.

FIGS. 1 and 2 relate to prior art methods, and are not to scale. FIG. 1shows a bead 200 of adhesive as dispensed onto a substrate 210 from anozzle 230, moving in a direction A, parallel to the substrate,according to an existing process. The nozzle 230 is held above thesubstrate, substantially above the top surface of the bead 200, and sothe nozzle is not in contact with the dispensed material. If there is alarge bubble in the dispensed material, there will be a break 220 in thebead 200.

FIG. 2 is a transverse section through the bead 200, showing a typicalshape profile of the bead on the substrate 210. The top surface 240 ofthe bead 200 is substantially semi-circular in profile. To achieve adispensed adhesive bead quantity of 2 g/m², the bead 200 is typically 1mm high and 2-3 mm in diameter.

FIG. 3 is a functional block diagram showing elements of a roboticdispensing system for use with one embodiment of a device 1 according tothe present invention. The interaction between each of the functions isnot intended to limit the invention to such conceptual distinctcomponents and it will be appreciated by those skilled in the art thatpractical embodiments could incorporate two or more functions in onecomponent. The device 1 is adapted to be connected to a robot 2 using arobot interface 3. A kinematic control 4 is provided to maintain themovement of the nozzle in predetermined planes. A force control 5 isincorporated to modulate and control an applied force on a nozzle 6towards the substrate 210 on which a fluid 8 is to be laid. The nozzle 6is in fluid communication with feed lines 13 connected to a conventionalproduct reservoir 14, which may be pressurised by an air supplied to thereservoir by a compressed air line. The fluid 8 which is to be dispensedor laid on the substrate passes from the product reservoir 14 throughthe nozzle 6 and onto the substrate 210.

FIG. 4 is a drawing showing a section through a cylindrical dispensingnozzle 6 illustrating in a diagrammatic and non-limiting manner theinteraction between the nozzle and dispensed fluid on the substrate,according to the invention. The nozzle 6 has an inner conduit 12 with anentry port 7 and an exit port 9 which is defined by an end portion 10 ofthe nozzle. The end portion 10 has an annular end surface 10 a which isa flat surface arranged parallel to the substrate 210 and having an edge10 b which defines the perimeter of the end portion. The nozzle 6 isconnected to a supply of liquid or paste product 8, which is typicallyanaerobic adhesive. An applied force F1 acts on the nozzle in adirection towards the substrate 210. The laying on of the fluid 8 ontothe substrate 210 effects a thrust upwards against the end portion 10 ofthe nozzle and the fluid still contained within the inner conduit 12,equivalent to a force F2 acting upwards. This force F2 is related to thepressure integral of the dispensed fluid acting against the area withinthe perimeter of the end portion 10 of the nozzle. The pressure exertedby the dispensed fluid on the end portion of the nozzle is not constantacross the end portion. Due to the interaction between the dispensedfluid and the fluid at the exit port 9, the pressure profile across theend portion is such that the pressure is large at the exit port 9 andreduces in magnitude to atmospheric pressure at the edge portion 10 b ofthe end portion 10. As fluid is dispensed, the fluid exerts a pressureupwards causing the nozzle to move away from the substrate, whileappearing to float on the dispensed product. The pressure is exertedboth on the end portion of the nozzle and on the fluid present in theexit port. This buoyancy of the nozzle 6 is resultant from anessentially hydrostatic thrust bearing on the nozzle, with the buoyantupward force F2 counteracting the downward force F1. It will beunderstood that FIG. 4 shows a static condition wherein there is nomovement of the nozzle along the substrate, and excess dispensed fluidbulges up and about the end portion of the nozzle.

As described previously, anaerobic adhesives cure in the absence of air.Their cure mechanism is, however, sensitive to metals and therefore thenozzle is preferably manufactured from a plastics material such aspolyacetal, PTFE or other suitable materials which are chemicallyneutral with respect to the fluid material and will not initiate curingof the product. It is also possible to use stainless steel or othersuitable materials by passivating them. When applied to a metal flange,the metal in the flange acts as an initiator to initiate the curing ofthe adhesive. On a non-metallic substrate, a primer may be used. Bybringing two substrates together it is possible to exclude air from theadhesive and cause the curing process.

In order to facilitate the placement of the adhesive fluid product 8 ona flange or other suitable substrate 210, it is necessary that thedispensing nozzle move about the substrate in a predetermined fashion.The movement of the dispensing nozzle may be achieved by attaching thenozzle to a robot (FIG. 3) and or some other suitable means.

FIG. 5 is a drawing showing the effect of the movement (in the directionof arrow A parallel to the substrate) of the nozzle 6 of FIG. 4, on thedispensed ribbon of adhesive product 8. As the nozzle 6 moves it trailsa bead of adhesive behind the nozzle. The top surface 11 of the bead isflattened or smeared, the smearing being achieved by the smoothingeffect of the end portion 10 and edge portion 10 b of the nozzle 6 onthe dispensed adhesive. As the nozzle moves, as controlled by the robot(FIG. 3), adhesive is laid from the exit port onto the substrate 210,and trails behind the nozzle, being smeared in the process to form aribbon 70.

If there are any bubbles in the dispensed fluid product these will tendto burst and vent towards the perimeter of the nozzle. The presence ofsuch an air bubble at the exit port will cause a momentary drop inthrust exerted by the dispensed fluid 8 on the end portion 10 of thenozzle, resulting in the upwardly acting force F2 being less than F1. Asthe device always tries to maintain F2 at the same magnitude as F1, thenozzle will tend to move in a direction towards the substrate 210,thereby reducing the gap between the end portion of the nozzle and thesubstrate. The height of the nozzle from the substrate affects theheight or thickness of the dispensed ribbon relative to the substrate,so that the movement of the nozzle towards the substrate results in athinner smear of adhesive on the substrate than would otherwise occur,but will not normally cause a break in the ribbon. The passage of theair bubble away from the exit port, such that normal product is beingdispensed, re-establishes the upwardly acting force F2, causing thenozzle to move in a direction away from the substrate until F2 is inequilibrium with F1 so that normal application of the adhesive resumes.The passage of the bubble away from the dispensing tip, such that normaladhesive is being dispensed, re-establishes the thickness of thedispensed ribbon.

FIGS. 6-10 show an embodiment of the device 1 of the inventionincorporating a dispensing nozzle 60 mounted for vertical free movementrelative to a robot arm 3, and a horizontal substrate 210. Variouscomponents of the device 1 that were shown in the functional blockdiagram of FIG. 3 are shown in practical embodiments in this drawing.The robot (FIG. 3) is programmable and is adapted to move the robot armaround the contours of the substrate 210 (FIGS. 9 and 10). When therobot arm moves, the dispensing nozzle 60 moves with the motion of therobot arm and the product gets smeared behind the nozzle, as wasdescribed with reference to FIG. 5. It will be understood that as thenozzle is connected to the robot arm, the movement of the robot armparallel to the substrate also effects a movement of the nozzle in thesame direction or plane as that of the robot arm. The nozzle is,however, also free to move in a direction substantially perpendicular toplane of movement of the robot arm, such free movement being effected bythe interaction between the nozzle, the dispensed fluid product and thesubstrate.

The nozzle 60 is connected to a pneumatically operable valve 22, whichhas a pneumatic actuator element 22 a. As seen in FIG. 10, the nozzlehas an inner conduit 12 leading to exit port 9 which is defined by athin-walled cylindrical end portion 10. The nozzle is screwed usingscrew thread 60 c into a corresponding portion of the valve 22 until anupper ledge portion 60 a of the nozzle butts against the lower face 22 bof the valve. The entry port 7 of the nozzle is thus connected to thevalve. The valve is secured using a mounting retainer 15 b (FIG. 6)which is attached to a mounting bracket 15 a using retainer screws 15 c.The mounting bracket/retainer combination form a base 15 which whenmated with a spring housing 23 form angled valve bracket 24, which istypically L-shaped.

The rear portion of the spring housing 23 is mated with a channel-shapedreceiver 26 which when slideably mounted on a monorail 27 forms aslideway 28 perpendicular to the substrate 210. The monorail 27 issecured to an angled mounting flange 17 comprising a leg 29 and baseportion 30. The mounting flange 17 is secured at a mechanical interfaceto a robot arm 3. A spring 20 is positioned and housed within a boresection 50 that extends through the valve bracket 24 and into the baseportion 30 of the angled mounting flange 17. The base 51 of the spring20 is compressed against the base portion 30 by the action of theadjustment screw 21, through a spring support 52. The compression on thespring can be pre-adjusted to a substantially constant pre-determinedforce by altering the position of adjustment screw 21. The advantage ofusing a spring is that one can precisely adjust the downward force to aload which is accurately known. In this embodiment, the net appliedforce F1 acting on the nozzle towards the substrate is comprised of thegravitational weight of the overall components, i.e. the nozzle, thevalve and the valve bracket, modulated by the force effected by thespring 20 acting in an upward direction, away from the substrate. Thislatter force acts away from the substrate thereby modulating thegravitation force effected by the weight of the components. As thespring is confined within a bore section 50, the length of which can beadjusted by means of the spring support 52 and the adjustment screw 21,it is possible to predefine the compression state that the spring 20 isinitially in, thereby predefining the force effected by the spring in anupward direction, modulating the downwardly acting gravitational force.

It will be understood by those skilled in the art that the spring 20described above forms a spring component, which has been illustrated formeans of convenience as comprising a spring. It is not intended to limitthe spring component to a physical spring as it will be appreciated thatmany spring equivalents are known in the art and are also applicable tothis situation.

As the receiver 26 is slideably mounted on the monorail 27 the valvebracket 24 can move relative to the mounting flange 17 in a directionperpendicular to the substrate 210. The extent of movement isconstrained at the lower end by the abutment of the base portion 30 andmounting bracket 15 a. The slideway 28 is incorporated so as to ensuresmooth action in one axis only, i.e. a kinematic control. The slidewayshown in FIGS. 6 to 9 is a slide table, which is an off-the-shelfstandard component such as for example model number VRT1025A availablefrom THK Co. Ltd of Japan. It will be appreciated that any component orset of components which act in the same manner could also be utilised.The downward force F1 necessary to maintain the nozzle in a downwardlyacting motion is provided in this embodiment by the weight of thecomponents, mainly the valve 22 and its mounting bracket 24. As thisembodiment is being described with reference to the application of aribbon of adhesive onto a horizontal planar substrate 210, it will beappreciated that the applied force in this embodiment is effectively agravitational force which is modulated by the counter-acting controlledspring 20, which is in compression.

Additionally, a support bracket or retainer 16 is also attached to theflange 17. Two supply tubes, a product feed tube 13 and pneumaticcontrol tube 18 are secured by the support retainer 16 before beingconnected to valve 22 and to a pneumatic motor control component 22 a ofthe valve 22, respectively. The securing of the supply tubes to thesupport retainer 16 minimises any drag effect on the valve 22 by thesupply tubes when the nozzle moves relative to the flange 17.

As described above the means for mounting the nozzle may suitablycomprise slide means such as a slideway or other guide means in whichonly one component is allowed to move to and fro in one axis ordirection relative to another component. One component suitablycomprises the moveable nozzle and the other component is secured to therobot arm.

By incorporating the valve 22 near the point of application it ispossible to better control the flow, particularly at both of the startand the end of the dispensing procedure, than having the valve at theproduct supply container. The desirability of the valve is due to theelastic nature of the product supply line elements and of the dispensedproduct which can result in a time lag between the stopping orinitiating of dispensing.

The slideway 28 and support bracket 16 form the kinematic controlfunctional block 4 referred to in FIG. 3. The support bracket 16additionally is part of the force control functional block 5 in that itserves to control the force exerted by the supply lines on the valve 22and thus on the nozzle.

It is common in many applications that the product to be dispensed isremotely located from the dispensing nozzle. As such it is necessary totransfer the product from its reservoir to the dispensing nozzle. Suchtransport is normally achieved using product supply lines. In thisembodiment, it is also necessary to incorporate pneumatic tube(s) 18 forcontrolling the operation of the dispensing valve 22. The effect of suchproduct and control lines can induce a variation on the loading on thenozzle due to the motion of the robot, which variation can causefluctuations in the amount dispensed. It is important to maintain aconstant vertical loading to ensure a consistent ribbon of gasketproduct.

The purpose of using a support bracket 16 for the product 13 and thepneumatic tubes 18 is to maintain the vertical component forcessubstantially constant. The loading associated with the product andpneumatic tubes can cause variations in the loading of the nozzle, andas such reduce the quality of the applied liquid gasket. Support bracket16 isolates the floating nozzle from the variable loading of the tubesas the robot moves. The bracket 16 is secured to the mounting flange 17,and moves with the robot arm 3 but does not move with the valve 22.

The force acting towards the substrate can be provided in one of manyways: it is possible to springload the nozzle either with a mechanicalspring or pneumatic actuator or it is possible to use selected weightswhich will supplement the gravitational force towards the substrate. Byaltering the downward force applied towards the substrate it is possibleto alter the thickness of adhesive product that is applied to thesubstrate. It will be appreciated that the abutment of the base portion15 a against the base 30 of the mounting flange 17 as shown in FIG. 8represents the lowest positioning of the nozzle relative to the mountingflange. In the drawing of FIG. 9 as the device is brought closer to thesubstrate 210 using the movement of the robot arm, so as to initiatedispensing, the interaction between the nozzle, dispensed product on thesubstrate and substrate (force F2) will effect a movement of the valvebracket base portion 15 a away from the base 30 of the mounting flange17, in a similar manner to that described with reference to FIGS. 4 and5. The receiver 26 of the slideway is higher on the monorail 27 than isshown in FIG. 8, so that the nozzle is free to move up and down relativeto the substrate 210.

For applications where gravitational forces are insufficient orunsuitable for effecting a force towards the substrate it will beappreciated that an alternative loading arrangement will be required.

In an alternative embodiment, shown in section in FIG. 11, only thenozzle 600 floats or moves with respect to the substrate 210. The nozzlehas an exit port 9 defined by an end portion 10, the exit port 9separated from the entry port 7 by an inner conduit 12. The nozzle ismounted within a bellows arrangement 33, which allows movement of thenozzle within the constraints of a generally cylindrical guide 36. Thelower portion 37 of the bellows is attached to a tapered upper portion38 of the nozzle and the upper portion 39 of the bellows is constrainedwithin a receiving portion 40 formed within the guide 36. The guide 36has an end portion 40 a which is penetrated by a supply bore 40 baligned with the conduit 12 of the nozzle. The space defined by thebellows 33, the upper face 32 of the nozzle 600 and the end portion 40 aof the guide 36 forms a dispensing well 31 to which the dispensablematerial is supplied under pressure. In use the nozzle 60 is free tomove within the constraints of the nozzle guide 36 and bellow 33, whichact as components of the kinematic control described in FIG. 3. Anapplied force F1 is generated by the pressure exerted by the product,while in the dispensing well 31, on the upper face 32 of the nozzle. Byconstraining the nozzle within the bellows type arrangement 33, andmounting the guide 36 with its axis perpendicular to the axis, thenozzle 600 is free to move towards and away from the substrate 210depending on the magnitude of the upwardly acting force F2, which willfluctuate as described previously. In this arrangement the movement ofthe nozzle 600 is independent of the other components of the apparatusand therefore the product and pneumatic tubes (see FIG. 6) do not affectthe floating portion of the system, and no bracket 16 is required torestrain the tubes. Nevertheless, it is practical to incorporate a valve22 which controls the flow of fluid at the start and completion of thedispensing procedure.

Although the chamfered portion 41 of the end portion 10 will affect thecharacteristics of the pressure profile across the end portion themethodology of the effect is the same as previously described.

FIG. 12 illustrates a nozzle in a further embodiment of the presentinvention. Similarly to that described with reference to FIG. 11, inthis embodiment the nozzle 600 is free to move independent of theremaining apparatus. The nozzle is mounted within the constraints of aguide 36, which defines the degree of movement allowable to the nozzle60. In the upper portion 61 of the nozzle 60 a circumferential channel62 is formed which serves as a receiver for an O-ring 63 which isslideable relative to an inner wall of the guide 36. A dispensing well31 is defined between the upper face 32 of the nozzle and a channel 64which supplies dispensable material from the product reservoir. TheO-ring 63 acts as a seal between the dispensing well 31 and the outerportion of the nozzle 60, thereby preventing the passage of productbetween the nozzle 60 and the guide 36. A stop member 35 is mounted onthe outer portion of the guide 36. The abutment of a ledge 65 on thenozzle 60 against the stop member 35 prevents the nozzle falling fromthe bottom of the guide 36. This abutment, as illustrated in FIG. 12,shows the lowest possible position of the nozzle and in a similar mannerto that described with reference to FIG. 8 would represent in use, theresting of the nozzle on the substrate. Similarly to that described withreference to FIG. 11 the applied force is generated by the force exertedby the fluid on the upper face 32 of the nozzle 60 while present in thedispensing well 31. The additional stop member 35 is incorporated torestrict the nozzle 60 in its degree of freedom.

The embodiments of FIGS. 11 and 12 can also be used to apply adhesive tonon-horizontal substrates. e.g., vertical substrates, the nozzle beingmounted for free movement substantially perpendicular to the substrate.

FIGS. 13 and 14 are perspective views of an alternative mounting methodfor the nozzle of the present invention. Differing from that disclosedwith reference to FIGS. 6 to 10, in this embodiment the valve is notpositioned directly above the dispensing nozzle. The same referencenumerals are used for similar components, which are operable in asimilar manner to that previously described. A support flange 170,similar to that of the flange 17 is provided, on which is mounted aslideway 28 comprising a receiver 26 slideably mounted on a monorail 27.The receiver 26 is mateable to a nozzle support housing 310 which allowsa free vertical movement of the nozzle support housing 310 relative tothe support flange 170 in a direction substantially perpendicular to ahorizontal substrate. In a similar manner to that described previously,the compression on the spring 20, which is housed within a bore section50 of the support housing 310, is adjustable using an adjustment screw21. The extent of motion of the nozzle support housing 310 is limited inthe downward direction by an abutment of the lower face 310 a of thesupport flange against the base portion 30.

The embodiment illustrated in FIGS. 13 and 14 differs from thatpreviously disclosed in the position of the valve relative to thedispensing nozzle. In this embodiment the valve is not seated orsituated directly above the nozzle, and the weight of the valve istherefore not acting on the slideway 28. The support flange 170additionally comprises a valve support 300 which is separate from thenozzle support housing 310. The valve support 300 is adapted to supportand mate with a valve 22 and its associated pneumatic motor controlcomponents, pneumatic control lines and product feed lines (as shown inFIGS. 6 and 7). By providing the valve with an independent support meansdirectly connectable to the support flange 170, there is no movement,during use of the apparatus, of the valve relative to the support flange170. The downward force F1 necessary to maintain the nozzle in adownwardly acting motion is provided in this embodiment by the weight ofthe moveable components, mainly the nozzle support housing 310. Themovement of the nozzle 60 relative to the substrate is independent ofthe valve and there is therefore no requirement to utilise means such asthe support retainer 16 to minimise any drag effect introduced bymovement of the product and pneumatic feed lines. A second product feedline 320 is provided between the valve support 300 and the nozzlesupport 310 so as to effect the controlled provision of product to theinner conduit of the nozzle for dispensing.

By utilising a nozzle as hereinbefore described it is possible to applyhigh quality ribbon of applied adhesive in quantities an order ofmagnitude smaller than previously achievable. The quality of the ribbonrefers to the lack of breakage in the applied ribbon. FIG. 15 is atransverse section across a ribbon 70 of adhesive 8 on a substrate 210as applied using a device of the present invention. The ribbon issmeared on dispensing by a nozzle (FIGS. 4 to 14) so as to form asubstantially flat surface 11. The curved edge portions 71 result fromsome seepage of the dispensed adhesive beyond the surface defined by thenozzle end portion, and surface tension effects.

As used herein the term “degree of movement” or “degree of freedom” ismeant a mode of motion with respect to a co-ordinate system, independentof any other mode. The term will be well understood by those in the artwho will appreciate that the nozzle of the present invention whenattached to a robot arm is moveable with the robot arm in the “x” and“y” direction about the substrate, thereby applying dispensing productto different regions of the substrate. At the same time the inventionprovides a nozzle capable of also moving in the “z” direction, themovement in the “z” direction being a movement substantiallyperpendicular to the substrate, which will be understood also effects amovement of the nozzle relative to the robot arm. This movement, ordegree of movement, in the “z” direction is effected by the interactionbetween the nozzle end portion, the dispensed product and the substrate.

The quality of the beading is related to the size of the outsidediameter of the nozzle and the absence of breaking of the ribbonoccurring during dispensing. In one example using a nozzle the outsidediameter of the end portion of which was 4 mm, and the exit port definedby said end portion 3 mm, it was possible to apply a ribbon of width 5mm. This ribbon had a thickness of approximately 200 μ, which equates toan applied product of approximately 1 g/m². When equated to thedispensed bead discussed with reference to the prior art methods it willbe realised that the method of the present invention facilitates theapplication of adhesive of higher quality on the substrate, yet does notrequire the same volume to be dispensed.

Example of Product Viscosity

The viscosity of product to be used with the device and method of thepresent invention include the following:

Product DIN viscosity (mP · s) Anaerobic Adhesive 1  7,500 AnaerobicAdhesive 2 55,000 Anaerobic Adhesive 3 55,000 Anaerobic Adhesive 420,000 Anaerobic Adhesive 5 90,000

Example of Dispensing Procedure

1. As there is no dispensable material initially present in the exitport of the nozzle, if the nozzle was positioned on the substratesurface no buoyant force would be present and the nozzle would rest onthe surface. To obviate this resting on the nozzle, the apparatus ispositioned initially using the robotic arm such that the nozzle is at aheight approximately 50 mm above the start point on the flange on whichthe adhesive is to be dispensed.

2. The valve is opened to allow the product to flow.

3. The apparatus is moved using the robot towards the substrate, withthe open valve ensuring that there is product at the nozzle end portionby the time the nozzle assumes the position at the start of the tracingrun. The nozzle does not come into contact with the substrate but ratheris presented to dispensed material on the substrate.

4. A ribbon is traced on the flange by movement of the nozzle on itsrobot arm in a predetermined manner.

5. Once the trace is completed, the valve is closed.

6. The apparatus and attached nozzle are moved away from the substrate.

The first three steps are to ensure that there is product present at theexit port at the start of the tracing procedure. A “squeeze film”, theterm defining the situation when two flat surfaces approach with aliquid in between, results from the presence of the product between thenozzle and the substrate. This squeeze film minimises the possibility ofthe nozzle coming into contact with the substrate, reducing thepossibility that the nozzle is contaminated by any material present onthe substrate.

Suitably the product reservoir is pressurised in the range from 2 bar to40 bar, more particularly 2 bar to 10 bar, and/or an auxiliary pump isprovided in the supply line between the reservoir and the valve toincrease the pressure of the product into the ranges mentioned above.The pressure will vary depending upon various factors, including theviscosity of the product and the nature of the equipment on the supplyroute between the reservoir and the nozzle. There is a loss of pressurealong the supply line, so that the pressure at the exit port of thenozzle is likely to be less than 1 bar.

The invention has been described with particular reference to anaerobicadhesives/sealants. However the invention is also applicable to otherfluid dispensable materials, particularly such materials which carry asignificant content of air or other gases.

Words such as “top”, “above”, “upper”, “lower”, “upwards”, “downwards”,“height”, “up and down”, “floats” and the like are used herein withreference to the positions of the device and/or the components thereofillustrated in the drawings and do not necessarily relate to thepositions adopted when the device is in use. Such terms are used withoutlimiting effect. The words “comprises/comprising” and the words“having/including” when used herein with reference to the presentinvention are used to specify the presence of stated features, integers,steps or components but do not preclude the presence or addition of oneor more other features, integers, steps, components or groups thereof.

While described in detail here, many modifications and equivalentsthereof will be clear to those persons of ordinary skill in the art andare intended to be covered hereby, the full measure of the spirit andscope of the invention being defined by the claims.

I claim:
 1. A device for the dispensing of a fluid dispensable materialin ribbon form to a substrate comprising: a) a robot arm programmable tomove about the substrate in a plane substantially parallel to thesubstrate, b) at least one dispensing nozzle having at least one innerconduit leading to exit port and adaptable to be in fluid communicationwith a supply source for the fluid dispensable material, the nozzlehaving an end portion defining the exit port such that a ribbon ofdispensed fluid material can be applied to the substrate, c) means formounting the nozzle for substantially perpendicular free movementrelative to the substrate such that at least part of the end portion ofthe nozzle maintains contact with the fluid material applied to thesubstrate, movement towards the substrate being effected by an appliedforce and movement away from the substrate being effected by a thrustexerted by the dispensed fluid material against said end portion of thenozzle and the dispensable material in the exit port, d) a slidemounting means for mounting the nozzle relative to the robot arm, theslide mounting means allowing free movement of the nozzle to andrelative to the robot arm in a direction substantially perpendicular tothe plane of movement of the robot arm, e) a spring component acting onthe slide mounting means, and f) adjustment means acting on the springcomponent so that an applied force on the nozzle is modulated tomaintain equilibrium between movement of the nozzle towards thesubstrate and away from substrate during the dispensing procedure. 2.The device as claimed in claim 1 wherein the means for mounting thenozzle maintain an equilibrium between the movement towards thesubstrate and movement away from the substrate during the dispensingprocedure, with the thrust exerted by the dispensed fluid material beingsubstantially equal in magnitude to the applied force such that thenozzle floats on the dispensed ribbon of material.
 3. The device asclaimed claim 1 wherein the thrust exerted by the dispensed fluidmaterial against the end portion of the nozzle and the fluid present inthe exit port is equivalent to an buoyant force.
 4. The device asclaimed in claim 3 wherein a perimeter of the nozzle end portion definesa reaction area against which the buoyant force, which is related to apressure integral of pressure exerted by the dispensed material on thereaction area, may react.
 5. The device as claimed in claim 1 whereinthe at least one nozzle is a single nozzle having a single innerconduit, the end portion of which is preferably an annular shapedsurface.
 6. The device as claimed in claim 1 wherein the end portion ofthe nozzle is mounted so that an end force thereof is substantiallyparallel to said substrate.
 7. The device as claimed in claim 1 whereinthe end portion has an outside diameter in the range from about 2.5 mmto about 10 mm and the exit port defined by said end portion has adiameter in the range 1 mm to about 5 mm.
 8. The device as claimed inclaim 1 for dispensing an adhesive and preferably an anaerobic adhesive.9. The device as claimed in claim 1 for dispensing a fluid whose DINviscosity is in the range from about 7,500 to 90,000 mP.s.
 10. Thedevice is claimed in claim 1 wherein the nozzle is connected to a valve,an upper ledge portion of the valve butting against a lower face of thevalve and the means for mounting the nozzle for substantiallyperpendicular free movement relative to the substrate allows a movementof the valve and nozzle combination.
 11. The device as claimed in claim1 wherein the nozzle is in fluid communication with a valve, the valvebeing located remotely from the nozzle and the means for mounting thenozzle for substantially perpendicular free movement relative to thesubstrate allows no movement of the valve.
 12. The device as claimed inclaim 1 further comprising a spring component, wherein the applied forcecomprises a gravitational force component effected by the weight of themeans for mounting the nozzle acting in a direction towards thesubstrate modulated by the force effected by the spring component actingin a direction away from the substrate.
 13. An apparatus for dispensinga fluid product onto a substrate, the apparatus comprising a nozzle andmeans for mounting the nozzle with at least one degree of freedomallowing movement of the nozzle relative to the substrate, with movementtowards the substrate being effected by a substantially constant forceacting on the nozzle and movement away from the substrate being effectedby a force related to the pressure exerted by the dispensed fluid on thenozzle.
 14. The apparatus as claimed in claim 13 wherein thesubstantially constant force which effects movement towards thesubstrate comprises a gravitational component modulated by acounter-acting spring component, the magnitude of the substantiallyconstant force being chosen so as to be substantially equal in magnitudeto the force effecting movement away from the substrate.
 15. Theapparatus as claimed in claim 13 wherein the nozzle is in fluidcommunication with a product reservoir which is pressurised such thatthe product is dispensed under pressure.
 16. The apparatus as claimed inclaim 13 having means for mounting the nozzle such that the interactionbetween the nozzle and the dispensed product allows the nozzle to adjustits height relative to the substrate as a result of variations in thedispensed product.
 17. The apparatus as claimed in claim 13 wherein thenozzle has an inner conduit leading to an exit port and adapted to be influid communication with the product reservoir, the nozzle having an endportion, the diameter of the end portion being 10 to 30% smaller thatthe width of the fluid product to be dispensed on the substrate.
 18. Amethod for dispensing a fluid dispensable material to a substratecomprising the steps of a) mounting a dispensing nozzle, in a mannerwhich allows substantially perpendicular free movement of the nozzlerelative to the substrate, b) facilitating the application of an appliedforce on the dispensing nozzle to effect movement of the nozzle in adirection towards the substrate, and c) supplying the fluid dispensablematerial to an exit port which is defined by an end portion of thenozzle, applying the material to the substrate and controlling theapplied force in relation to a thrust exerted by the dispensed fluidmaterial on the end portion of the nozzle and the dispensable materialtherein such that the end portion of the nozzle maintains contact withthe dispensed material applied to the substrate.
 19. The method asclaimed in claim 18 wherein the fluid is laid onto the surface in aribbon of material.
 20. The method as claimed in claim 19 wherein thethrust exerted by the dispensed fluid is substantially equal inmagnitude to the applied force such that the nozzle floats on thedispensed fluid.
 21. The method as claimed in claim 18 wherein thethrust exerted by the dispensed fluid on the nozzle is a buoyant forcewhich is related to one or more of the following: a) the pressureexerted by the dispensed fluid on the nozzle end portion, b) thepressure exerted by the dispensed fluid on the fluid material at theexit port, and c) the distance of the nozzle away from the substrate,wherein the nozzle adjusts its position relative to the substrate as aresult of fluctuations in the magnitude of said buoyant force.
 22. Themethod as claimed in claim 18 wherein a ribbon of dispensed fluidmaterial is applied onto the substrate at a thickness greater than thesurface roughness of the substrate.
 23. The method as claimed in claim18 wherein the pressure exerted by the dispensed fluid on the nozzle isless than the force acting towards the substrate so that the nozzlerides on the substrate resulting in local points of contact between thesubstrate and the nozzle.
 24. A method for dispensing a fluiddispensable material from a nozzle to a substrate comprising the stepsof a) supplying the fluid dispensable material to an exit port which isdefined by an end portion of the nozzle, b) applying the material to thesubstrate, c) smearing the applied material with the end portion of thenozzle, the width of the applied smeared material on the substrate beingrelated to the diameter of the end portion of the nozzle.
 25. The methodas claimed in claim 24 wherein the width of the applied smeared materialis about 10% to about 30% larger than the diameter of the end portion ofthe nozzle.
 26. A device for the dispensing of a fluid dispensablematerial in ribbon form to a substrate comprising: a) a robot armprogrammable to move about the substrate in a plane substantiallyparallel to the substrate, b) at least one dispensing nozzle having atleast one inner conduit leading to an exit port and adaptable to be influid communication with a supply source for the fluid dispensablematerial, the nozzle having an end portion defining an exit port suchthat a ribbon of dispensed fluid can be applied to the substrate, and c)means for mounting the nozzle for substantially perpendicular freemovement relative to the substrate such that at least part of the endportion of the nozzle maintains contact with the fluid material appliedto the substrate, movement towards the substrate being effected by anapplied force and movement away from the substrate being effected by athrust exerted by the dispensed fluid material against said end portionof the nozzle and the dispensable material in the exit port.